Perimeter

1
Perimeter Area of Rectangles
Parallelograms
6-1
Warm Up
Problem of the Day
Lesson Presentation
Pre-Algebra
2
Learn to find the perimeter and area of
rectangles and parallelograms.
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Vocabulary
perimeter area
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Any side of a rectangle or parallelogram can be
chosen as the base. The height is measured along
a line perpendicular to the base.
Parallelogram
Rectangle
Height
Height
Side
Base
Base
Perimeter is the distance around the outside of a
figure. To find the perimeter of a figure, add
the lengths of all its sides.
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Additional Example 1A Finding the Perimeter of
Rectangles and Parallelograms
A. Find the perimeter of the figure.
Add all side lengths.
P 14 14 5 5
38 units
Perimeter of rectangle.
or P 2b 2h
Substitute 14 for b and 5 for h.
2(14) 2(5)
28 10 38 units
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Additional Example 1B Finding the Perimeter of
Rectangles and Parallelograms
B. Find the perimeter of the figure.
P 16 16 20 20
72 units
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Try This Example 1A
A. Find the perimeter of the figure.
6
11
Add all side lengths.
P 11 11 6 6
34 units
Perimeter of rectangle.
or P 2b 2h
Substitute 11 for b and 6 for h.
2(11) 2(6)
22 12 34 units
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Try This Example 1B
B. Find the perimeter of the figure.
5
13
P 5 5 13 13
Add all side lengths.
36 units
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Area is the number of square units in a figure. A
parallelogram can be cut and the cut piece
shifted to form a rectangle with the same base
length and height as the original parallelogram.
So a parallelogram has the same area as a
rectangle with the same base length and height.
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Additional Example 2A Using a Graph to Find Area
Graph the figure with the given vertices. Then
find the area of the figure.
A. (1, 2), (2, 2), (2, 3), (1, 3)
Area of a rectangle.
A bh
Substitute 3 for b and 5 for h.
A 3 5
A 15 units2
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Additional Example 2B Using a Graph to Find Area
Graph the figure with the given vertices. Then
find the area of the figure.
B. (0, 0), (5, 0), (6, 4), (1, 4)
Area of a parallelogram.
A bh
Substitute 5 for b and 4 for h.
A 5 4
A 20 units2
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Try This Example 2A
Graph the figure with the given vertices. Then
find the area of the figure.
A. (3, 2), (1, 2), (1, 3), (3, 3)
Area of a rectangle.
A bh
Substitute 4 for b and 5 for h.
A 4 5
A 20 units2
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Try This Example 2B
Graph the figure with the given vertices. Then
find the area of the figure.
B. (1, 1), (3, 1), (5, 3), (1, 3)
Area of a parallelogram.
A bh
Substitute 4 for b and 4 for h.
A 4 4
A 16 units2
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Additional Example 3 Finding Area and Perimeter
of a Composite Figure
Find the perimeter and area of the figure.
6
6
3
3
6
5
5
The length of the side that is not labeled is the
same as the sum of the lengths of the sides
opposite, 18 units.
P 5 6 3 6 3 6 5 18
52 units
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Additional Example 3 Continued
6
6
3
3
6
5
5
A 6 5 6 2 6 5
Add the areas together.
30 12 30
72 units2
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Try This Example 3
Find the perimeter of the figure.
The length of the side that is not labeled is 2.
2
4
6
7
7
6
2
2
P 6 2 4 7 6 4 2 2 2 7
?
42 units
4
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Try This Example 3 Continued
2
Find the area of the figure.
4
6
7
Add the areas together.
A 2 6 7 2 2 2 4 2
7
6
2
2
12 14 4 8
2
2
38 units2
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Lesson Quiz Part 1
1. Find the perimeter of the figure.
12 ft
5 ft
4 ft
5 ft
5 ft
5 ft
44 ft
12 ft
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Lesson Quiz Part 2
2. Find the area of the figure.
12 ft
5 ft
4 ft
5 ft
5 ft
5 ft
108 ft2
12 ft
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Lesson Quiz Part 3
Graph the figure with the given vertices and find
its area.
3. (4, 2), (6, 2), (6, 3), (4, 3)
50 units2
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Lesson Quiz Part 4
Graph the figure with the given vertices and find
its area.
4. (4, 2), (2, 2), (3, 5), (3, 5)
42 units2